000 AXNT20 KNHC 221804 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1805 AM EST Fri Nov 22 2019 Tropical Weather Discussion for North America, Central America Gulf of Mexico, Caribbean Sea, northern sections of South America, and Atlantic Ocean to the African coast from the Equator to 32N. The following information is based on satellite imagery, weather observations, radar and meteorological analysis. Based on 1200 UTC surface analysis and satellite imagery through 1745 UTC. ...SPECIAL FEATURES... Tropical Storm Sebastien is centered near 25.2N 55.3W at 22/1500 UTC or 600 nm NE of the Northern Leeward Islands moving ENE at 13 kt. Estimated minimum central pressure is 1000 mb. Maximum sustained wind speed is 45 kt with gusts to 55 kt. Numerous moderate with isolated strong convection is from 25N to 30N between 49W and 55W. An ENE to NE motion is expected during the next few days. Continued gradual weakening is anticipated and Sebastien is forecast to dissipate by early next week. The Public Advisories for Sebastien are available via AWIPS/WMO headers MIATCPAT5/WTNT35 KNHC. The Forecast/Advisories for Sebastien are available via the AWIPS/WMO headers MIATCMAT5/WTNT25 KNHC. ...TROPICAL WAVES... A tropical wave is in the central Atlc from 01N to 10N with axis near 36W, moving W at 10-15 kt. Scattered moderate isolated strong convection is from 0N to 11N between 25W and 38W. A tropical wave is to the SE of the Windward Islands from 06N to 14N with axis near 56W, moving W around 10 kt. Isolated showers are S of 10N between 51W and 60W. ...MONSOON TROUGH/ITCZ... The monsoon trough passes through the coastal plains of Sierra Leone near 07N12W to 07N14W. The ITCZ continues from 07N14W to 05N20W to 05N32W, then continues W of a tropical wave from 02N37W to 01N46W to 0N50W. For information on convection, see the Tropical Waves section. GULF OF MEXICO... Except for isolated showers and patchy fog along the NW Gulf coast, the remainder basin is under fair weather conditions being supported by a deep-layered anticyclone centered near the Yucatan Peninsula in the middle to upper levels. At the surface, the ridge is anchored by a 1022 mb high over the SW N Atlc and provides gentle to fresh return flow to the gulf as seen in the latest ASCAT pass. The surface ridge will prevail across the area through today. A cold front will move off the Texas coast and into the NW Gulf this evening, cross the northern and central waters this weekend, then weaken and stall over the southern Gulf Sun night into Mon. Another cold front may move into the NW Gulf by Tue night. CARIBBEAN SEA... A surface trough, remnants of a former tropical wave, is over the NW Caribbean waters extending from 19N82W to Nicaragua adjacent waters. Isolated showers are in the vicinity of this trough. The remnants of a former cold front are analyzed as a shearline extending from Guadeloupe SW to 15N67W to 14N73W. Scattered to isolated showers are within 60 nm either side of the shearline. This line of showers and tstms will gradually move SSE through Sat and then dissipate. Otherwise, the pressure gradient between T.S. Sebastien in the central Atlc and high pressure building over the SW N Atlc waters is supporting a swath of fresh winds N of 14N between the Mona Passage and the Dominican Republic. These winds will diminish Sat as Sebastian is expected to continue a NE track, which will weaken the pressure gradient. Easterly trades will freshen across the south-central Caribbean early next week, increasing to strong Tue into Tue night. ATLANTIC OCEAN... Please, see the Special Features section above for details on T.S. Sebastien. A cold front is just west of T.S. Sebastien extending from 22N61W to near Puerto Rico. The front will continue moving eastward and steer Sebastien into the north-central Atlantic. Surface high pressure is over the SW N Atlc waters and will prevail through Sat, then shift eastward Sat night. The next cold front will cross the region Sun through Mon, weakening near 70W Tue and Tue night. Otherwise, surface ridging domintes the northeastern Atlc waters. $$ NR